Bolt locking mechanism for reciprocating gun

ABSTRACT

A bolt locking mechanism for an automatic weapon having a bolt housing and an accelerator slidably mounted therein. A firing pin is attached to the accelerator and the bolt housing has a pair of linear grooves extending outwardly to the sides of the bolt. A roller lock is provided in each linear groove and these roller locks are engageable with cams which lock the accelerator with the bolt during a portion of the bolt travel. A barrel extension has a pair of locking grooves which are engageable by the roller locks to lock the bolt housing with the barrel extension during firing of the automatic weapon.

[ Nov. 19, 1974 BOLT LOCKING MECHANISM FOR RECIPROCATING GUN [75]Inventor: John F. Wolpert, Louisville, Ky.

[73] Assignee: The United States of America as represented by theSecretary of the Navy, Washington, DC.

[22] Filed: Aug. 27, 1973 [21] Appl. No.: 391,701

[52] US. Cl. 89/173, 89/187 CB [51] Int. Cl. F41d 5/02 [58] Field ofSearch 89/153, 173, 174, 180,

153,875 7/1938 Austria 89/173 Primary Examiner-Stephen C. BentleyAttorney, Agent, or Firm-R. S. Sciascia; Paul S. Collignon S 7 ABSTRACTA bolt locking mechanism for an automatic weapon having a bolt housingand an accelerator slidably mounted therein. A firing pin is attached tothe accelerator and the bolt housing has a pair of linear groovesextending outwardly to the sides of the bolt. A roller lock is providedin each linear groove and these roller locks are engageable with camswhich lock the accelerator with the bolt during a portion of the bolttravel. A barrel extension has a pair of locking grooves which [56]References Cited are engageable by the roller locks to lock the boltFOREIGN PATENTS OR APPLICA'HONS housing with the barrel extension duringfiring of the 945,216 7/ I956 Germany 89/187 automatic weapon. 945,8l97/1956 Germany 89/188 0 955,392 1/1957 Germany 89/188 1 Claim, 7 DrawmgFigures BOLT LOCKING MECHANISM FOR RECIPROCATING GUN BACKGROUND OF THEINVENTION The present invention relates to a breech locking mechanismfor automatic weapons. In automatic weapons, such as machine guns, abreech head or block is provided in a housing and is locked theretoduring the igniting of a cartridge. After firing, the breech block isautomatically unlocked from the housing and then reciprocated by eitherrecoil or by gas pressure in order to extract a spent cartridge and theload a live cartridge into the gun chamber. As modern day weapons mayfire five or six hundred rounds per minute, the design of breech blocklocking mechanisms is highly critical as wear and fatique on thecontacting elements will cause the weapon to jam and malfunction.

Various devices have been used to lock a breech to a housing duringfiring. For example, in U. S. Pat. No. 3,348,453, which issued Oct. 24,1967, to Ernest Muhlemann, a pair of bolt locks are pivotally connectedto a bolt mechanism and these locks are engageable with slots in thebreech housing. The bolt mechanism is unlocked by a control member whichmoves rearwardly and permits the bolt locks to retract.

SUMMARY OF THE INVENTION The present invention relates to an improvedbreech locking device for an automatic weapon. A bolt housing has anaccelerator slidably mounted therein and a firing pin is attached to theforward end of the accelerator. A pair of roller locks are mounted inlinear grooves in the bolt housing and cams are provided to hold theroller locks in engagement with the accelerator to prevent forwardmovement. The cams permit the roller locks to move outwardly as the boltmoves forward and unlocks the accelerator from the bolt housing. Theroller locks are engageable with grooves in a barrel extension and canlock the bolt housing to the barrel extension during firing. The rollerlock is of a two-piece construction having a cylindrical ring which ismounted or supported on a shaft having flats thereon which engage in thelinear groove.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of amachine gun using the bolt mechanism of the present invention;

FIG. 2 is a partial sectional view showing a bolt FIG. 7 is a side viewof a bolt mechanism.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring first to FIG. 1 of thedrawing, there is shown a machine gun 11 having a recoil barrel 12attached to gun housing 13. By way of example, gun 11 might be anair-cooled weapon that fires from 350 to 600 rounds of ammunition perminute, with the ammunition being fed into the gun by a mechanicalfeeder while the rounds are presented in a continuous link belt.

Referring now to FIGS. 2 through 7 of the drawings, barrel 12 isattached, as by threading, to barrel extension 14 which is part ofhousing 13. Barrel extension 14 is provided with a bore 15 for receivinga cartridge 16 and is also provided with a chamber 17 for receiving abolt 18 which chambers cartridge 17 prior to firing and extracts thespent cartridge after firing. An accelerator 19 is slidably mounted inbolt 18 and carries a firing pin 21. Bolt 18 is provided with a pair oflinear grooves 22 and 23 which are opposed one another and extend to thesides of bolt 18. Roller lock assemblies 24 and 25 are positioned ingrooves 22 and 23, respectively, and are used to retain accelerator 19until cartridge 16 is fully chambered. A pair of cams 26 and 27 areprovided on the sides of housing 13 and are used to facilitate lockingand unlocking of roller lock assemblies 24 and 25.

As best shown in FIG. 7 of the drawaings, each roller lock assembly iscomprised of a shaft 28, which has flat sides engageable with the sidesin the groove in which it operates, and a roller 29 is provided on shaft28 and is engageable with one of the cams. Barrel extension 14 isprovided with a pair of cam grooves 31 and 32, and these grooves areengageable by the roller lock assemblies 24 and 25, respectively.

OPERATION Firing action of the weapon shown in FIG. 1 of the drawingsbegin when bolt 18 is released from a sear in a manner well-known in theart. A round 16 on the lower face of the bolt is chambered, while around in the feeder is being picked up on the upper face of the bolt. Amore complete description of this loading operation can be found in U.S. Pat. No. 3,563,132, which issued FEB. 16, 1971, to Cashen et al.

Bolt 18 is driven forward by a drive spring (not shown) and, as bolt 18moves into battery position, roller lock assemblies 24 and 25 moveoutwardly into grooves 31 and 32, as best shown in FIG. 4 of thedrawings. As shown in FIG. 5 of the drawings, as the roller lockassemblies move completely into grooves 31 and 32, accelerator 19 isfree to move forward, and inertia bar 33 drives accelerator 19 forwardthereby forcing firing pin 21 into the primer of round 16. As round 16fires, the recoil components of weapon 11 begin their rearward movement,with bolt 18 still being locked to barrel extension 14. When roller lockassemblies 24 and 25 engage cams 26 and 27, these roller lock assembliesare cammed inwardly and bolt 18 is unlocked from barrel extension 14.Roller lock assemblies 24 and 25 then move accelerator l9 rearwardlywith respect to bolt 19 and then again lock accelerator 19 with bolt 18.

By way of example, with weapon 11 being chambered to fire 20mmammuition, when bolt 18 begins its rearward movement, bolt 18 pullsbarrel extension assembly about 1% inches before roller lock assembliesare cammed inwardly to free the bolt 18 from barrel extension 14. Abarrel recoil spring then forces barrel extension 14 back into a firingposition.

It can be seen that roller lock assemblies 24 and 25 are retained inlinear grooves 22 and 23, respectively, and that shaft 28 has flats sothat there is area contact between shaft 28 and the groove in which itoperates.

These features greatly reduce the stress levels on rollers 29 and thusprevent wear and malfunction.

It can thus be seen that the present invention provides an improved boltlocking mechanism for an'automatic weapon. Obviously many modificationsand variations of the present invention are possible in the light of theabove teachings. It is therefore to be understood, that within the scopeof the appended claims, the invention may be practiced otherwise than asspecifically described.

I claim:

1. In an automatic firearm, a bolt locking mechanism comprising,

a breech housing,

a barrel extension connected to said breech housing having means forattaching a barrel on one end thereof and having locking groovestherein,

a bolt slidably mounted in said breech housing, said bolt having opposedlinear slots with parallel surfaces in each side thereof,

an accelerator slidably mounted in said bolt, said accelerator having afiring pin attached thereto,

first and second roller lock assemblies each said rolcam means attachedto said breech housing engageable with said roller lock assemblies forlocking said accelerator with said bolt until a round carried by saidbolt reaches a battery position and said roller lock assemblies unlocksaid accelerator from said bolt and lock said bolt to said barrelextension and upon recoil of said bolt said cam means actuates saidroller lock assemblies to unlock said bolt from said barrel extensionand to lock said accelerator with said bolt.

1. In an automatic firearm, a bolt locking mechanism comprising, abreech housing, a barrel extension connected to said breech housinghaving means for attaching a barrel on one end thereof and havinglocking grooves therein, a bolt slidably mounted in said breech housing,said bolt having opposed linear slots with parallel surfaces in eachside thereof, an accelerator slidably mounted in said bolt, saidaccelerator having a firing pin attached thereto, first and secondroller lock assemblies each said roller lock assembly having a shaftwith at lesst one pair of flat parallel surfaces on each end thereof anda roller positioned midway between said shafts ends with said flatparallel surfaces extending outwardly from each side of said roller,said parallel surfaces on each end of said shaft being slidablyengageable with the parallel surfaces of said linear slots in said boltand each said roller being engageable with said accelerator, said rollerlock assemblies releasably locking said accelerator with said bolt, andcam means attached to said breech housing engageable with said rollerlock assemblies for locking said accelerator with said bolt until around carried by said bolt reaches a battery position and said rollerlock assemblies unlock said accelerator from said bolt and lock saidbolt to said barrel extension and upon recoil of said bolt said cammeans actuates said roller lock assemblies to unlock said bolt from saidbarrel extension and to lock said accelerator with said bolt.